Sheet metal normalizing furnace



E. E. MCVEY ET AL. 1,858,678

Filed Feb. 2s, 1929 z sheetssneet 1 Nrn May 17, 1932.

SHEET METAL NORMALIZING FURNACE Patented May 17, 1932 UNITED 'STATESSELLIER E. MCVEY, OF YOUNGSTO'WN,

PATENT OFFICE SHEET METAL NORMALIZING FURNAC'E Application illedFebruary 23, 1929. Serial No. 341,925.

Our invention relates to that class of furnaces employed foi'normalizing metal sheets or the like by subjecting them tol heat for thepurpose of eliminating the effects of the strains and stresses incidentto the preceding rolling or other operations, among the principalobjects of the invention being to provide a normalizing furnace soconstructed as to be capable of normalizing a much greater quantity ofmaterial in a given time than the normalizing furnaces heretofore in useand at a materially lower cost per ton of material treated; to provide anormalizing furnace in which `the principles of recuperation andregeneration are employed in such manner as to preheat the incoming coldsheets by heat radiated from the outgoing hot sheets whereby materialeconomy in fuel cost is effected through utilization for the performanceof useful work of a large amount of heat which would otherwise beentirely lost, and to provide a normalizing furnace so constructed thatthe sheets to be normalized may be fed thereinto from opposite ends ofthe furnace and moved therethrough in opposite directions whichlresults, among other things, in substantially doubling the capacity ofthe furnace without a corresponding increase in its size, thisconstruction also permitting the normalizing in a single normalizingfurnace of sheets supplied from separated furnaces, mills or othersources and at a far less fuel cost than would be required fornormalizing a like quantity| of sheets in two separate normalizingfurnaces of the type usually heretofore employed and respectivelylocated adjacent the separate sources of sheet supply.

Further objects of the invention are the provision of a normalizingfurnace embodying means for rapidly reducing the temperature of thesheets passing therethrough after the same have been raised to thetemperature required for normalization so as to quickly bring about apractical fixation of the fine grain structure of the metal; to providea normalizing furnace having a central hot or final temperature zone anda cooling zone adjacent each end thereof and which embodies a system ofbailles or equivalent means whereby the heat supplied to the finaltemperature zone is in large measure confined Y thereto and prevented`from escaping therefrom.

Still further objects of the invention are to provide a normalizingfurnace in which accurate temperature regulation may be read- 11yobtained, which is satisfactorily and eiliciently operative for-theperformance of its intended function, and in which, in that embodimentthereof which is generally preferred, the heat for normalizing thesheets 1s applied to the latter both from above and from below.

Our invention additionally includes other objects and novel features ofdesign, construction and arrangement hereinafter more particularlypointed out or which may be apparent to those skilled in the art fromthe following description of certain embodiments of our invention asillustrated in the accompanying drawings.

In said drawings, Fig. 1 is a fragmentary longitudinal vertical centralsection through one form of normalizing furnace constructed inaccordance with our invention; Fig. 2 is an enlarged transversevertical-section on line 2-2 1n Fig. 1 and Fig. 3 is a fragmentarytop-plan view, partiallyin horizonal section, of some of the conveyorrolls and adjacent parts. In Figs. 5, 6 and 7, which respective- 'lycorrespond to the ligures just described, we vhave illustrated anormalizing furnace constructed in accordance with another embodiment ofour invention and in which the conveyor rolls, instead of beingsuperposed as in the first form, are arranged side 4by side in the samehorizontal plane as will hereinafter more fully appear. Thus Fig. 4 is afragmentary longitudinal vertical central section through the furnace,Fig. 5 an enlarged transverse vertical section on line 5-5 v of Figi/J:and Fig. 6 a fragmentary top plan view of'some of the conveyor rolls andadjacent parts. The same symbols of reference are used to designate likeparts in the several figures, and all sectional views are taken in thedirections indicated by the arrows on the section lilies.-

Referring now more particularly to that embodiment of the inventionillustrated in Figs. 1, 2 and 3, the furnace, as best shown 1n Fig. 1,is of elongated form and arranged to provide three zones through whichthe sheets are consecutively passed as they traverse the furnace fromone end to the other. These zones, respectively indicated by thebrackets More particularly the furnace comprises a roof 1 which maydesirably .be arched and supported on parallel, longitudinally extendingside walls 2 joined at their lower extremlties by a floor or hearth 3,the Walls and roof being formed of bricks or other suitable, preferablyrefractory, material. End walls 4 and 5 are. also provided, the formerbeing ierced with upper and lower openings form- 1ng doors 6-6 and thelatter with corresponding openings forming doors 7--7, all of thesedoors being desirab y in the form of transversely extending slots ofsufficient height to permit the introduction to and discharge from thefurnace of the sheetswhich vare to be normalized,l The furnace roof maybe rovided with a covering 1 of heat-insulating material to cut downradiation losses. The furnace is of maximum height throughout the lengthof the hot or final temerature zone b, and is desirably of slightlyesser height throughout the zone c and of still lesser height throu houtthe zone a, said zones, of course, being. m'the form of chambers 8, 9and 10 respectively bounded by the roof, sides and bottom of the furnaceand communicating with each other. The sidewalls and roof of the furnacemay be supported and tied together in the usual way by .buckstays 12 andtie rods13 as indicated in .l Fig. 2 or in any other suitable wayas-will be well understood by those familiar with the art.

In the form of the invention now being described two sh-eet conveyors,generally-,designated as 15 and 16, are provided and arranged one abovethe other in spaced relation. Each of these conveyors comprises aplurality of transversely extending shafts, those in the upper conveyorbeing designated as 17 and those in the lower as 18, respectvelyprovidedwith a plurality of laterally spaced discs'19rand 20 which are arrangedin staggered relation on each adjacent pair of shafts so as to form asupport for the sheets operativeV to convey them through the furnacewhen theshafts are rotated. The ends of the shafts are extended throughthe side walls of the furnace and any suitable means is pro-- vided fordriving them. Thus each ofthe upper shafts may be furnished at one e'ndwith a bevel gear 21 cooperative with, a similar gear 22 on a drivingshaft 23 extending horizontally along the side wall of the furnace andthe lower shafts similarly furnished of power and arranged to rotate inopposite directions so that the upper conve or 15 will be effective tomove the sheets t rough the furnace in one direction, for example asindicated by the arrow adjacent thereto, while the lower conveyor willbe effective to move'the sheets through the furnace in theopposite'direction as indicated by the adjacent arrow. The conveyorshafts may be journalled in supports 28 disposed outside of the furnaceand the side walls of the latter provided with apertures for .thepassage of the shafts of such size as to provide a certain amount ofclearance therefor so that the shafts, as well as the walls themselves,are free to expand and contract under changes of temperature vwithoutinterfering with the operation of the shafts. While we have shown theshafts as solid, it will of course be understood that if desired theymay bemade hollow and also that provision may be made for the effectinga circulation of water through them or for otherwise cooling them in anyof thevvarious ways commonly employed in the art.

The heat requisite for the normalizing operation is introduced to thehot or final temperature chamber 8 of the furnace by means of burnersextended through the side walls of the latter and we prefer to employfor this purpose an upper and a lower set of burners, the former beingdisposed adjacent the roof of the chamber and the latter adjacent thehearth 3 so that the heat will'be introduced to the chamber both aboveand below the conveyors. Thus, more particularly, we prefer to arrange aplurality of burners 30 at longitudinally'spaced intervals throughoutthe length of the cham-ber 8 and on opposite sides thereof so that theburning gases therefrom will be projected toward the center of thechamber-from each side thereof and preferably horizontally orsubstantially so, and we also provide another set of longitudinallyspaced burners 31 below the` lower conveyor on opposite sides of thechamber so that the burning gases from, these burners will likewise bedirected inwardly toward the center of the chamber from both.

to dispose thesel burners 4horizontally in a4 may be of any suitableconstruction and design adapted for the burning of gas, either naturalor artificiah'or any other desiredv heating medium, and are preferablycapable of individual regulation and soarranged that any desired numberof them may be employed simultaneously as it frequently happens that notall of the burners are reqlured to produce the requisite .heatingeffect.

In order to ,confine within the final temperature chamber 8 as much aspossible of' the heat derived from the burners` we provide between thischamber and the chamber 9 an upper baille 40 and a lower baliie 4l,these baflies preferably consisting of walls extending transverselyacross the chamber, the

baiiie .40 being disposed between the conveyors and the baille 41 belowthe lower conveyor. With the same end in view, We also provideadepending transversely extending baflle wall 42 adjacent the junctureof that portion of the furnace roof which is over the chamber 9 and thatwhich is over the chamber 8, this wall extending down to a point uitecloselyl adjacent Vthe upper surface of t e upper conveyor. At theopposite end of the final temperature chamber and for a like purpose, weprovide similar upper and lower baiiies 43 and 44 generallycorresponding to the bafiies 40 and 41,-but as the roof of the chamberl() is preferably, as hitherto stated, somewhat lower than theroof ofthe chamber 9 and thus lies 'more nearly adjacent the upper conveyor, itis ordinarily unnecessary to provide a depending bafHe wallcorresponding to the wall42 vat the juncture of the roof of the finalheating chamber and the recuperativel-jchamber l0.

As the sheets pass from the final temperature zone after having beenraised to the requisite normalizing heat therein, it is desirable toquickly reduce their temperature to a point at which further graingrowth is arrested and a practical fixation of the fine grain structuree'ected. We therefore provide means for bringing about a relativelyrapid reduction in the temperature of the sheets at this point in theirtraverse through the furnace, and while said means may be of any formsuitable for effecting the desired function we nd that good results maybe obtained by providing a plurality of transversely extending,flattened pipes 46 adjacent the inner end of the roof of therecuperative chamber 10 and thus substantially above the bames 43 and44, these pipes being suitably connected to a source (not shown) ofcooling fluid, such as Water, which is circulated through the pipes.Thus as the subjacent sheets S are moved past the relatively cool pipesthey are cooled or quenched to theVv requisite extent. Similarly and fora like purpose, we may provide a plurality of correspondingpipes 47adjacent the inner end of the recuperative chamber 9 and above the lowerconveyor so as to suitably-cool or quench the subj acent sheets S. asthey are carried past the pipes by this conveyor; these pipes 47 may beconveniently'supported on the under side of the baille 40 and connected,like the pipes 46, to a convenient source of cooling fluid supply. Asstated, however, While these flattened pipes, through which acirculation of cooling fluid is maintained,

are satisfactorily operative for effectingthe requisite rapid' coolingor quenching of` the sheets as they pass from-the final temperaturechamber, any other means suitable for the performance of this functionmay be employed in lieu thereof if preferred.

ln the operation of the furnace the sheets S either alone or supportedon a waster sheet are consecutively fed into the furnace through theupper door 7 in the end wall 5 and are then progressively carried by theconveyor entirely through the furnace and discharged therefrom throughthe upper door 6 at the opposite end thereof While in a similar waysheets S are-consecutively fed into the furnace through the lower door6, either singly or each supported on a waster sheet, progres-` sivelycarried through the furnace by the lower conveyor and nally dischargedtherefrom through the lower door 7 at the opposite end. Heat is ofcourse continuously supplied to the final temperature zone 8 insufficient quantity to bringthe sheets S to the requisite normalizingtemperature by the time they reach the left-hand end of this zone orchamber when viewed as in Fig.'1 and to similarly bring the sheets S tothe requisite-normalizing temperature by los the time'they reach theright-hand end of said zone or chamber. As the sheets S pass beneathVthe pipes 46 and similarly as the sheets S pass beneath the pipes 47,they are subjected to the action of the cooling medium which quicklylowers their temperature sufficiently to practically fix the fine grainstructure of the sheets and prevent further graingrowth therein; thecooling or quenching effect, however, is desirably regulated so that thetemperature of the sheets will not be reduced materially below the pointat which the desired fixation of grain-structure is effected whereby asthe sheets pass beyond their respective cooling or quenching points theystill retain a considerab-le amount of residual heat which is radiatedfrom the'sheets into tive .chamber 10 a considerable portion of theirresidual heat is given off within the chamber and'refiected downwardlyby the low Y roof thereof to the subjacent sheets on the conveyor 16which, entering the chamber through the lower door 6, are thusrogressively heated as they approach the fina temperature chamber 8 sothat upon entering the same they are much hotter than when introduced tothe fur- 10 nace with the result that they can be raised to the requirednormalizing temperature more quickly land with less. expenditure of heatthan would be required if they entered the filial temperature zone atthe temperature at v.15 which they were initially introduce to the-furducedto the furnace and thus need` less heat and less time to raisethem to the normalizing temperature than would otherwise be required.Additionally, the radiation of heat l which takes place from the hotsheets S or S as the case may be during .their passage -throughtherespective recuperative zones or chambers results, bythe time the sheetsare ready to pass ont of the furnace, in so reducing 36 the temperatureof the sheets-as to prevent the formation of scale thereon after theyare ejected from the furnace while, of course, all

of their heat'which has been transferred to the relatively cold incomingsheets has Vbeen vuse- 40 fully employed in reheating the latter andthus conserved andp utilized in .the performance of useful work withconsequent enhancement of economy of operation. u

A further advantage of our invention resides in the fact that whenwaster sheets are used as a support for the-sheets to be normalized andare thus ejected from the furnace with the latter at one end or theother there.-

of, they may be immediately separated from `l thenormalized sheets andused on the other conveyor as supports for the unnormalized sheets whichare passing into theV furnace fromA that end; 'the waster sheets beingthus returned to the furnace before all of the heat which they haveabsorbed in their passage therethrough is dissipated, a further economyyis effected through-the conservation in this manner of heat which isotherwise lostfif the waster sheets are'allowedl'to eoolto-.atmos- L30pheric temperaturel after leaving the furnace and before being returnedthereto.

" When normalizing sheets of the same -thickveyor is substantially thesame. However,

the furnace may be used with e ual facility for normalizing sheets` oftwo di erent thicknesses in which case as the thicker sheets naturallylrequire a longer time for normalization-under lthe same temperatureconditions than do the thinner sheets, that conveyor upon which theformer are carried through the furnace may be run at a lower speed thanthe conveyer transporting the. lighter sheets ,thereby maintaining theheavier sheets in the .furnace for the additional time required toproperly normalize them.

In Figs. 3, 4 and 5 we have shown a somewhat modified formvof ourinvention in which the conveyors, instead of being superposed, arearranged side by side thus ordinarily dccreasing the height ofgthefurnace but increasing its width for a given capacity.

Since ,in this form of the invention the construction of the side walls,bottom, roof and supporting means therefor are desirably substantiallysimilar to that heretofore described, extended reference thereto wouldbe superfiuous. As stated, however, theA furnace is usually made widerand lower as will be -apparent from an inspection of Fig. 5 and becauseof this decrease in height but a single 'set of burners 30'willgenerally be found sufficient, these burners being directed into thefinafl temperature zone justbelow the furnace roo Two horizontallyaligned series or sets of conveying rolls 50-and 5l are employed andextended respectively inward Athrough the side walls of the furnacewhich are provided with suitable openings for the passage thereof. Therolls are desirably of such length as lto leave av longitudinally.extending space between their adjacent inner ends along the center lineof the furnace and those portions of the rolls within the furnace areprovided with conveying discs 52, 53 corresponding to .the discs 19 and20 heretofore-described. The

outer end of the rolls beyond the side walls of the furnace may bejournaled in supports 55 and any suitable means provided for driv- `ingeach setof rolls, for example, sprockets and chains generallydesignatedas 57 and 58 may bev employed, or drive shafts and bevel gearing. of thegeneral character of that shown 1n connection with the form of theinventionheretofore described.

For confining the heat as much as possible within the final temperaturezone, the furnace may be provided with transverselyextending b-ailiewalls 60 and 61 beneath the conveyor rolls at the ends of the finaltemperature zone while quenching means 62 .and 63 corresponding to thequenching means 47 land 46 are ldisposed respectively above theconveyors so as to quench the sheets as they `passfrom the-finaltemperature zone in either direction, In this form of the invention,

p however, the quenching means, for example the inner ends of thesubja'cent conveyors and are thus respectively effective onlyupon thesheets carried thereby. v In this form of the invention the height ofthe recuperative 4chambers is' preferably the same, as shown in Fig. 4,instead of the roof of the chamber 9 being somewhat higher than thatofthe chamber 1 0 as in the other form of the invention previouslydescribed.;

thus there is no necessity for providing a transversely extending baiiiebet een cham-- ber 9 and the final temperature zo e corresponding tothebaiiie wall 42 in that form of the invention.

1n operation the two horizontal aligned series of conveyor rolls arerotated in opposite directions and the sheets S to be normalizedconsecutively fed thereto from opposite ends of the furnace so that theywill be. carried through the furnace in' opposite directions anddischarged from opposite ends thereof, the sheets being successivelyquenched by the superjacent quenching means as they pass from the naltemperature zone so as to effect substantial fixation of the grainstructure in the manner already described. Whenwaster sheets areutilized' for supporting the sheets to be normalized in their passagethrough the furnace, the waster sheets as they are discharged` therefromat the opposite ends thereof may be immediately returned to thefurnaceupon the other and oppositely moving conveyor so as to conservetheir heat as far as possible while, asin the .case of the other form ofthe invention, the heated sheets,

and waster sheets if used, after leaving the final temperature zone andduring their passage through'the recuperative chambers are effective toraise the temperature ofthe adjacent incming sheets so that the latterenter the final temperature zone in a pre-- heated condition withconsequent conservation of heat and reduction in operating costsasheretofore mentioned.

While we have hereinl described certain forms of our invention withconsiderable particularity, we do Vnotthereby desire orintend to conneourselves thereto nor to any precise details of design, construction andarrangement of the various parts, nor to the use of any particular form,number or arrangement of burners, as the same being a matter of choicemay be modiied in various ways and in numerous particulars withoutdepartingfrom the spirit and scope of the invention as defined in theappended claims.

Having thus described our invention, we claim and desire to protect byLetters Patent of the United States adjacent each end thereof andcommunicating therewith, a plurality of burners extended throughthe'walls of the central chamber and operable to heat said chamber to apredetermined temperature, means for'substantiall confining within thecentral chamber the eat generated by. the burners, adjacent conveyorsextending through all of said chambers Jand respectively adapted toprogressively carry material to -be normalized therethrough fromopposite ends of the fur.

nace along vertically spaced paths and opposite directions and meansdisposed adjacent the inner end of each recuperative chamber operable toquickly reduce the temperature of said material as it passes intosaidchamber from the central chamber.

2. A normalizing furnace comprising .a centralpchamber and arecuperative chamber 'adjacenteach end thereof and communicat ingtherewith, vertically spaced conveyors.

extending 'in opposite directions through all p of said chambers,burners projecting into the central chamber and adapted to heat thelatter to a predetermined temperature, means adjacent each end of thecentral chamber adapted to 'conne the heat therein, and

means adj acentsl .said last mentioned means operative to rapidly reducethe vtemperature of material disposed on the conveyors as it is carriedthereby from the central chamber into the recuperative chambers.

3. A normalizing furnace comprising a central chamber and arecuperativechamber adjacent each end thereof and communicating therewith, saidrecuperative chambers being of less height than the central chamber andrespectively of diiferent heights, a pair of vertically spaced conveyorsextending through all of said chambers and respectively -operable toconvey material through the furnace in opposite directions, burnersprojecting into the'central chamber and adapted to heat the latter to apredetermined temperature, means ad'acent each end of the centralchamber a apted to coniine the heat therein, and means adjacent saidlast mentioned means operative to rapidlyl reduce the temperature ofmaterial disposed on the conveyors as it is carried thereby from thecentral chamber into the recuperative chambers.

4. A normalizing furnace comprising' a central chamber forming a linaltemperature zone anda recuperative chamber adjacent each end thereof andcommunicating therewith, said recuperative chambers being of less heightthan the central chamber, a pair of superposed vertically spacedconveyors extending longitudinally through all of said chambers, meansfor driving the conveyors in opposite directions, burners extending intosaid central chamber operable to maintain the temperature of the latterat a predetermined degree and means adjacent the inner ends of therecuperative chambers operative to reduce the temperature of materialdisosed on the conveyors as it is carried therey out of the centralchamber and into the recuperative chambers.

Y 5,. A sheet normalizing 'furnace comprising a central chamber forminga final temperature zone and a recuperative chamber of less height thanthe central chamber adjacent each end thereof and communicating Ytherewith, a pair of sheet conveyors disposed one above the other andextendin longitudinally through all of said cham rs, means for drivingthe conveyors in opposite directions, burners extending into saidcentral chamber from opposite sides thereof operable ,to maintain thetemperature of the chamber at a predetermined degree,l means adapted toconfine the heat generated by said burners within the central chamber,and means adjav cent the inner end of each recuperative chamberoperative to quickly reduce the tempera- 'ture of the sheets as they areconsecutively carried by the conveyors in opposite directions -from thecentral chamber and into the recuperative chambers. v

In witnessA whereof we have set our hands this 19th day of February,1929.

ELMER MCVEY. WILLIAM -F. BARTHOLOMEW.

